ESTL to Present at ESMATS 2019
ESTL will be attending the 18th European Space Mechanisms and Tribology Symposium (ESMATS), hosted by OHB in Munich, Germany from the 18th – 20th September 2019. Four papers will be included from ESTL, covering a range space mechanisms and vacuum tribology subjects.
Torque-Based Life Indicators for Gears in Vacuum – Achilleas Vortselas
The in-orbit lifetime of spacecraft spur gear units is limited by lubricant failure, followed by scuffing and subsequently severe wear of tooth faces. This paper analyses torque data for solid, fluid and hybrid lubricated spur gears to determine which frequently used frequency- and time-domain condition monitoring indicators can detect the onset of gear lubrication distress and imminent wear-out prior to an increase in gear torque.
A Study of the In-vacuum Performance of Space Lubricants in a Compliantly Preloaded Pair of Angular Contact Ball Bearings Using the Advanced Bearing Test Rig – Simon Lewis
The recently developed Advanced Bearing Test Rig (ABTR) at ESTL has the capability of concurrent measurement of bearing torque, axial shaft displacement, preload, contact resistance, and temperature, for a pair of angular contact ball bearings operating in vacuum. This paper describes fluid film thickness estimation from axial shaft displacement and discusses the results of characterisation tests on four space (fluid) lubricants, including observations on lubrication regime transitions.
The Effect of Surface Production Techniques on the Tribological Behaviour of Fluid Lubricants – Rachel Bingley
When designing gears and bearings for space careful consideration must be given to their tribological surfaces. Often arithmetic mean roughness Ra is the only aspect of the surface finish specified on engineering drawings, though several other surface parameters exist which may influence the tribological properties of the contact. This paper investigates the behaviour of fluid lubricated surfaces with regard to the significant of these additional parameters, including skewness and kurtosis.
Ageing and Environmental Effects on Lubricants – A Preliminary Study – Michael Buttery
It is usually assumed that, when correctly applied, the properties of space lubricants remain essentially unchanged. However, evidence is emerging to suggest time-variable and environmental dependence of the tribological behaviour of some vacuum lubricants. Test activities performed by ESTL utilising both the Pin-on-Disc (PoD), Spiral Orbit Tribometer (SOT), and angular contact bearings have shown that the lifetime and frictional properties of space lubricants can be influenced by environment during both test and storage.
ESTL will also be hosting the prestigious Space Tribology Course in Munich on the two days preceding ESMATS (16th -17th September). For registration and more information regarding this course please visit www.esmats.eu/munich/home/register-and-pay-stc/